Preliminary studies into the behaviour of knee braced frames subject to seismic loading

Abstract A recently proposed structural system for earthquake-resistant steel-structures is investigated. This new framing system, called the knee braced frame (KBF), dissipates energy during severe seismic excitations through flexural yielding of the knee element. The lateral stiffness is provided by a conventional diagonal brace with at least one end connected to the knee element. As the performance of this framing system depends on the ductile behaviour of the knee element, this critical element was tested to confirm its behaviour under cyclic loading. An analytical model for the moment-rotation relationship of the knee element, derived from the bilinear stress-strain relationship obtained through tensile test, is found to predict the cyclic response of the knee element accurately. Using this analytical model, the energy dissipation characteristics of the KBF are presented.